1. Field of the Invention
The present invention is broadly concerned with improved knife assemblies of the kind commonly used with extruders to cut extrudate on a continuous basis. More particularly the invention is concerned with such knife assemblies and corresponding methods wherein the knife assemblies include an adjustment mechanism allowing easy and safe axial adjustment of the cutting knives relative to an extruder die.
2. Description of the Prior Art
Extruder systems for the production of comestible and other products typically include an elongated extruder barrel with an internal, axially rotatable auger serving to subject materials to be processed to high levels of shear and temperature. The barrel is equipped with an endmost extrusion die which serves to shape the materials as they are extruded. It is also common to provide a rotating knife assembly adjacent the die end of such an extruder barrel, in order to cut the extrudate to desired lengths. Such cut products then fall by gravity onto a conveyor belt or other similar equipment to transport the product away from the system.
The conventional knife assemblies in use today are deficient in several respects. First of all, it can be difficult and even hazardous to change the axial position of the rotating knives during operation. Indeed, in many cases it is necessary to stop the knife assembly and thus the entire system in order to adjust the knife position. Some on-the-go knife adjustment mechanisms have been proposed, but these are generally very complex and costly. For example, hydraulic devices have been tried, but these are not really satisfactory. Furthermore, some prior knife adjustment mechanisms were of the rotating type, i.e., the adjustment components normally rotate at knife speed.
In addition, it is sometimes difficult to properly gauge and determine the extent of knife wear during operation of conventional knife assemblies. This is important in that over-worn knives become inefficient and damage to the knife assembly can occur if the blades are excessively worn.
There is accordingly the need in the art for an improved knife assembly of the type used in extruder systems and wherein the knife assembly may be adjusted during and without interfering with cutting operations, and which make use of non-rotating adjustment components which can be manually manipulated by the operator. Furthermore, there is a need for such a knife assembly which can monitor the extent of blade wear during operation.
The following references are indicative of the state of the art. U.S Pat. Nos. 2,594,894; 3,029,466; 3,196,487; 3,266,090; 3,337,913; 3,353,213; 3,564,650; 3,673,298; 4,151,241; 4,184,833; 4,249,879; 4,285,652; 4,529,370; 4,728,276; 5,059,103; 5,146,831; 5,360,585; 5,836,225; 6,332,765; 6,604,929; US Publication No. 2007/0172533; German Patents Nos. 3436394; 3437495; European Patent No. 001576881; Great Britain Patents Nos. 0016891; 0848596; Japanese Patent No. 54-072261; and Russian Patent No. 0514707.